The Dinosaurs and Prehistoric Animals of New Mexico

Coelophysis fossil at the Natural History Museum in London

 Drow male / Wikimedia Commons / CC BY-SA 4.0

Each state boasts a fossil record revealing a variety of unique dinosaurs and other prehistoric animals, and New Mexico is no exception. It has an amazingly rich and deep fossil record. The geologic formations in this state stretch back nearly unbroken for over 500 million years, encompassing most of the Paleozoic, Mesozoic, and Cenozoic Eras. Way too many dinosaurs, prehistoric reptiles, and mammalian megafauna have been discovered there to list them all individually. Discover the most important fossil finds in New Mexico, ranging from the tiny dinosaur coelophysis to the huge prehistoric bird gastornis.

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A 3D modeled coelophysis, a dinosaur of New Mexico

Ballista / Wikimedia / CC BY-SA 3.0

The official state fossil of New Mexico, the fossils of coelophysis have been dug up by the thousands at the Ghost Ranch quarry, leading to speculation that this small theropod dinosaur (only recently evolved from the very first dinosaurs of South America) roamed the southwestern plains of late Triassic North America in vast packs. Coelophysis is also one of the few dinosaurs to show evidence of sexual dimorphism, males of the genus growing slightly larger than females.

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3D modeled nothronychus, a dinosaur of New Mexico who was a herbivorous cousin of T. rex

Getty Images

The long-necked, long-clawed, pot-bellied nothronychus was the first therizinosaur to be unearthed in North America; until this important discovery along the New Mexico/Arizona border, the most famous genus from this strange family of dinosaurs was the central Asian therizinosaurus. Like its relatives, nothronychus was a plant-eating theropod that used its long claws not to gut other dinosaurs and small mammals, but to rope in vegetation from tall trees.

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A fossilized parasaurolophus skeleton at the Field Museum in Chicago

Lisa Andres / Flickr / CC BY 2.0

The large, loud, long-crested parasaurolophus was initially discovered in Canada, but subsequent excavations in New Mexico have helped paleontologists identify two additional species of this duck-billed dinosaur (P. tubicen and P. cyrtocristatus). The function of parasaurolophus's crest? Most likely to honk messages to other members of the herd, but it may also have been a sexually selected characteristic (that is, males with bigger crests were more attractive to females during mating season).

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Various Ceratopsians

Ojoceratops fowleri, a Late Cretaceous-era dinosaur whose fossil remains were found in New Mexico

Sergey Krasovskiy / Stocktrek Images / Getty Images

Over the last few years, the state of New Mexico has yielded the remains of a huge number of ceratopsians (horned, frilled dinosaurs). Among the genera recently discovered in this state are the ornately frilled and horned ojoceratops, titanoceratops and zuniceratops; further study should reveal just how closely related these plant-eaters were to each other, and to more familiar ceratopsians like triceratops that lived in other parts of North America during the late Cretaceous period.

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Various Sauropods

Alamosaurs rendered in 3D

CoreyFord / Getty Images

Any state with as rich a fossil record as New Mexico is sure to yield the remains of at least a few sauropods (the giant, long-necked, elephant-legged plant-eaters that dominated the late Jurassic period). Diplodocus and camarasaurus were initially identified elsewhere in the U.S., but the type specimen of the 30-ton alamosaurus was discovered in New Mexico and named after this state's Ojo Alamo formation (and not the Alamo in Texas, as many people mistakenly assume).

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Various Theropods

Daemonosaurus, a dinosaur of New Mexico

Jeffrey Martz / DeviantArt

Coelophysis may be New Mexico's most famous theropod, but this state was home to a wide array of meat-eating dinosaurs during the Mesozoic Era, some (like allosaurus) having a long paleontological pedigree, and others (like tawa and daemonosaurus) counting as very recent additions to the theropod roster. Like coelophysis, many of these smallish theropods were only recently derived from the first true dinosaurs of nearby South America.

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Various Pachycephalosaurs

Stegoceras, a dinosaur of New Mexico

Sergey Krasovskiy / Stocktrek Images / Getty Images

Pachycephalosaurs ("thick-headed lizards") were bizarre, two-legged, ornithischian dinosaurs possessing thicker-than-usual skulls, which males used to head-butt each other for dominance in the herd (and possibly to flank-butt approaching predators). New Mexico was home to at least two important pachycephalosaur genera, stegoceras and sphaerotholus, the latter of which may turn out to have been a species of yet a third bonehead, prenocephale. 

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Coryphodon, a prehistoric mammal, at the American Museum of Natural History

Eden, Janine and Jim / Flickr / CC BY 2.0

One of the first true megafauna mammals, the half-ton coryphodon ("peaked tooth") was a common sight in swamps around the world during the early Eocene epoch, only 10 million years after the dinosaurs went extinct. Numerous specimens of this small-brained, large-bodied, plant-eating mammal have been discovered in New Mexico, which enjoyed a much lusher and more humid climate 50 million years ago than it does today.

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The Giant Bison

The fossilized skeleton of a giant bison, a prehistoric mammal of New Mexico

daryl_mitchell / Flickr / CC BY-SA 2.0


The giant bison—genus name Bison latifrons—roamed the plains of late Pleistocene North America well into historical times. In New Mexico, archaeologists have discovered giant bison remains associated with Native American settlements, a clue that the first human inhabitants of North America teamed up in packs to hunt this megafauna mammal to extinction (at the same time, ironically enough, as they worshiped it as a kind of natural demigod).

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Gastornis, a prehistoric bird of New Mexico

ZeWrestler / Wikimedia Commons / CC BY-SA 3.0

The early Eocene gastornis wasn't the biggest prehistoric bird that ever lived (that honor belongs to more colorfully name genera like the elephant bird), but it was one of the most dangerous, with a tyrannosaur-like build that demonstrates how evolution tends to adapt the same body shapes to the same ecological niches. One gastornis specimen, discovered in New Mexico in 1874, was the subject of a paper by the famous American paleontologist Edward Drinker Cope.

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Strauss, Bob. "The Dinosaurs and Prehistoric Animals of New Mexico." ThoughtCo, Feb. 16, 2021, Strauss, Bob. (2021, February 16). The Dinosaurs and Prehistoric Animals of New Mexico. Retrieved from Strauss, Bob. "The Dinosaurs and Prehistoric Animals of New Mexico." ThoughtCo. (accessed June 10, 2023).